Drop-In Chlorinator For Portable Spas

ABSTRACT

An oxidizer generating apparatus comprising a cylindrical housing and an electrode assembly attached at one end of the housing comprising at least three vertically disposed electrodes, the electrodes being spaced apart so as to define a water flow path between them, the electrodes comprising titanium outer electrodes and at least one inner diamond electrode

PRIORITY CLAIM TO EARLIER FILED APPLICATIONS

The teachings herein constitute a divisional application of applicationSer. No. 14/815,579, filed Jul. 31, 2015, which is a continuation ofapplication Ser. No. 14/262,576, filed on Apr. 25, 2014, which is acontinuation of application Ser. No. 13/570,658, filed on Aug. 8, 2012and issued as U.S. Pat. No. 8,745,774 on Jun. 10, 2014, which is acontinuation of application Ser. No. 12/504,49, filed on Jul. 16, 2009and issued as U.S. Pat. No. 8,266,736 on Sep. 18, 2012, and the benefitof these earlier filing dates are claimed and the content thereofincorporated herein by reference as though fully set forth herein.

FIELD OF INVENTION

This disclosure relates to water purification particularly with respectto water containing vessels such as spas, hot tubs, whirlpools, poolsand the like and to a chlorinator or oxidizer generator suitable forsuch purpose.

RELATED ART

Portable spas have become quite popular as a result of their ease of useand multiplicity of features such as varied jet and seatingconfigurations. Maintaining appropriate water chemistry and sanitationis of course important to enhancing the spa user experience.

SUMMARY

The following is a summary of various features, aspects, and advantagesrealizable according to various illustrative embodiments of theinvention. It is provided as an introduction to assist those skilled inthe art to more rapidly assimilate the detailed discussion which ensuesand does not and is not intended in any way to limit the scope of theclaims which are appended hereto in order to particularly point out theinvention.

An illustrative embodiment of a portable spa drop-in chlorinatorincludes a housing having an inlet at a first end, wherein an electrodeassembly is mounted so that spa waters flows through the electrodes andout of a second end of the device. When an appropriate voltage isapplied, the electrodes interact with the fluid within the chlorinatorto generate various oxidizing agents. In one embodiment, the chlorinatoris cylindrical and is sized to fit within the central opening of afilter element located in a filter compartment of a portable spa.

In one embodiment, respective outer electrodes comprise titanium, whileinner electrodes comprise doped diamond particles embedded in a plasticmesh substrate. In other illustrative embodiments, the doped diamondsurface comprises the surface of a whole diamond electrode. In otherillustrative embodiments, the diamond coated substrate may be selectedfrom one of the group including titanium, niobium, silicon, platinum, orstainless steel. The electrodes may be solid metal plates or a mesh, thelatter providing increased surface area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a drop-in chlorinator according to anillustrative embodiment;

FIG. 2 is a top view of the chlorinator of FIG. 1;

FIG. 3 is a sectional view of the chlorinator of FIG. 1 taken at 3-3 ofFIG. 1;

FIG. 4 is a schematic perspective view of an illustrative electrodeassembly embodiment;

FIG. 5 is a top end perspective view of a drop-in chlorinatorillustrating an electrode assembly according to FIG. 4 encapsulated inthe device;

FIG. 6 is a top view of a second electrode assembly embodiment;

FIG. 7 is a top schematic view illustrating one implementation of theelectrode assembly of FIG. 6;

FIG. 8 is a top schematic view illustrating a second implementation ofthe electrode assembly of FIG. 6;

FIG. 9 illustrates one method of fabricating the assembly of FIG. 6;

FIGS. 10-12 are side schematic views illustrating various applicationsof chlorinators according to the illustrative embodiments; and

FIG. 13 is a side exploded view of a drop-in chlorinator assembly usefulin the application of FIG. 12.

DETAILED DESCRIPTION

FIGS. 1-3 depict an illustrative embodiment of a compact drop-inchlorinator 11. The chlorinator 11 has a cylindrical housing 13. Anelectrode assembly 15 comprising electrodes 25, 27, 29, 31 is disposedvertically through the interior of the housing 13 and retained in thehousing 13, for example, by surrounding epoxy potting compound 17. In anillustrative embodiment, epoxy 17 fills the interior of the cylinder 13except for the space occupied by the electrode assembly. An electricalcable 19 supplies the device 11 with power and is also encapsulated bythe epoxy potting compound 17. Respective end caps 16, 18 enclose theopposite ends of the housing 13 and assist in shielding the electrodeassembly 15 from foreign matter, and are optional in variousembodiments.

In one embodiment, spacers 20 may be used to space the electrodes apart.As seen in FIG. 5, the epoxy potting may overlap the spacers 20 andedges of the electrodes 25, 27, 29, 31 to hold the assembly 15 inposition.

As illustrated in FIG. 4, the electrode assembly 15 comprises a pair ofouter electrodes and a number of inner electrodes. In the illustrativeembodiment of FIGS. 1-4, an outer electrode pair 21 and two innerelectrodes 23 are provided. In this embodiment, the outer electrode pair21 comprises a pair of rectangular titanium electrodes 25 and 29, whilethe inner electrodes 23 comprise rectangular diamond electrodes 27 and31. Electrical leads L₁, L₂ emanating from the cable 19 are welded orotherwise electrically connected to the respective titanium electrodes25, 29. The inner electrodes 27, 31 float electrically, i.e., are notconnected to ground. Additional inner electrodes, for example, up totwenty, may be provided in alternate embodiments.

In one embodiment, the titanium electrodes 25, 29 comprise titaniumcoated with ruthenium iridium. The diamond electrodes 27, 31 maycomprise 0.250 micron boron doped diamond crystals embedded in a teflonsheet (plastic matrix) such that diamond protrudes from each side of thesheet. The plastic matrix can be polytetrafluoroethylene (PTFE),polyvinylidene fluoride (PVDF), polyethylene, polypropylene or othersuitable materials. In alternate embodiments, the diamond electrodes cancomprise either a coating on a substrate or whole diamond designed to beself supporting.

In a second electrode assembly embodiment 18 shown in FIG. 6, a singlecentral rectangular diamond electrode 41 is positioned betweenrespective titanium outer electrodes 43, 45. In one embodimentillustrated in FIG. 9, the electrode assembly 18 of FIG. 4 is tightlywrapped in a solid plastic film or tape 49 to keep the epoxy pottingmaterial out of the assembly 18 during fabrication. Again, theelectrodes 41, 43, 45 may be separated and positioned by nonconductive,e.g. plastic mesh spacers 55 (FIG. 7) or individual plastic spacers 57(FIG. 8). The central diamond electrode 41 floats electrically, i.e., isnot connected to ground. The ends of the plate electrodes 43, 43 may bepassivated, e.g., ruthenium iridium coated to avoid corrosion andcalcium scale.

Illustrative uses of a drop-in chlorinator are shown in FIGS. 10-12.FIG. 10 shows an “over the bar top” application where the electrodecable 19 extends over the top edge of the spa 101 and suspends thechlorinator 11 in a floating position in the spa water.

FIG. 11 illustrates an embodiment wherein the electrical cable 19 passesthrough a pass through seal 107 in the sidewall 104 of the spa 101 intothe spa tub or filter compartment, suspending the chlorinator 11 in oneof those areas. The “dry” side 103 of the cable 19 may be located in theelectrical equipment area of the spa 101 where it may interface with thespa controller circuitry as hereafter described in more detail

In the embodiment of FIG. 12, the electrical cable 19 enters the filtercompartment 105 and is dropped down the central cylindrical opening 106of a filter element 107. In this position, spa water is pulled throughthe electrode assembly, e.g. 15, of the unit 11 by the pump of the spawater circulation system. Thus, the diameter of the cylindricalchlorinator 11 is selected to fit down the internal pipe of the filterelement 107. The chlorinator 11 may of course be located elsewhere inthe circulation path of the spa. While a snug fit between thechlorinator 11 and internal filter pipe is shown in FIG. 12, a looserfit is preferred, for example, providing a difference of 0.25 inchesbetween the respective diameters of the two parts. In one illustrativeembodiment, the drop-in chlorinator may be 1.3 inches in diameter andsix inches in length or otherwise properly sized to fit down a filterstand pipe.

A drop-in chlorinator assembly particularly useful in the embodiment ofFIG. 12 is illustrated in FIG. 13. That assembly includes a chlorinator11, a stand pipe cap assembly 109, and a pass through assembly 111. Thediameter of the pipe section 113 of the cap assembly 109 is selectedsuch that it fits snugly into the central cylindrical opening in thefilter element 107, while the diameter of the rim 115 of the cap portion117 is such that it abuts the top surface 121 of the filter element 107.A strain relief device 119 is further provided and, when assembled, isattached to the cable 19 in the interior of the cap assembly 109. Thechlorinator 11 is thus suspended with the filter element 107 at aposition determined by the length of L₃ of the cable 19. The passthrough assembly 111 includes a strain relief providing nut 122, a passthrough fitting 123 and first and second 9-rings 125, 127.

In various alternate embodiments, the electrodes are rectangular inshape and each comprise a boron doped synthetic diamond electrodetailored to flow rate. Such electrodes may be formed, for example, bychemical vapor deposition (CVD) of a very thin coating of boron ornitrogen doped diamond onto a niobium substrate. Such electrodes may befabricated, for example, by Adamant, Chauxde-Fords, Switzerland. Othersubstrate materials may be used such as titanium, silicon, platinum orstainless steel. Embodiments may also be constructed of self-supportingdiamond without using a substrate, such as may be obtained, for example,from Advanced Oxidation, Cornwall, U.K. In various embodiments, thesubstrates may either be solid plates or mesh, the latter providingincreased surface area.

In operation of illustrative embodiments in an illustrative portable spaenvironment, a constant current mode of operation of the device 11 maybe employed. In such case, a selected current flow through eachelectrode pair in the range of 1-5 amps, for example, 2 amps, may beused with a floating voltage across the outer electrode pair of 5-24volts. In such embodiments, flow rates through the cell 11 may rangefrom ½ gallon to 5 gallons per minute. An advantage of the chlorinatoraccording to embodiments above is that it has low salt levelrequirements (0 ppm to 1000 ppm) vs. typical 3500-5000 ppm.Electronically, a constant current AC/DC transformer supplying 1 to 5amps at 5 to 24 volts D.C. may be used along with a microcontroller tocontrol activation of the chlorinator 11.

In such embodiments, hydroxyl radicals are generated directly off theelectrode plates. The hydroxyl radicals then oxidize organic waste inthe process water or react with water and dissolved salts to producevarious oxidizers. These include but are not limited to, ozone (O3),hydrogen peroxide (H2O2), sodium hypochlorite (NaHOCI/OCl), chlorinedioxide (ClO2), sodium persulfates (NaHSO5) and sodium percarbonate(Na₂CO₃). This broad spectrum of oxidizers is capable of neutralizingorganic and other contaminants which may be present.

A chlorine generator system according to an illustrative embodiment mayoperate in an open-loop mode using scheduled and timed generation ofchlorine. The length and interval of daily generation is typically afunction of the spa size, bather load, and water salinity. In such asystem, the cell 11 may produce a constant stream of 0.1 to 0.60 ppm(parts per million) chlorine in a 4 gpm flow (0.5-2 amp & 1000-2000 ppmsalt). To maintain the chlorine level in the water, the cell 11 mustoperate longer for a large spa than for a small spa. Additionally thecell 11 must run longer with a higher expected bather load. The saltlevel has a strong direct relationship to the quantity of chlorineproduced.

In an illustrative open loop system the user inputs three variables tothe system at start-up. The first is the SPA SIZE or (SPA). A size codemay be used (e.g. 1-8). The anticipated USE LEVEL or (USE) (1-5) is thesecond variable. Use level “(1)” corresponds to minimal use and vacationmode. A higher level should be entered if more bathing is expected. Theuser preferably adjusts the use level over the course of use. The thirdstart-up variable input is the water hardness (Hd). This parametercontrols the polarity reversal cycle timing used to clean theelectrodes. This variable may not be employed in alternate embodiments.

As an additional input feature, a manual chlorine addition (Add) orBOOST command may be implemented. This command instructs the system togenerate enough chlorine to add 2 ppm to the spa. This chlorine Addtemporarily overrides scheduled operation times.

The manual Add or BOOST command dictates that the system run for alength of time sufficient to add 2 ppm Chlorine. The amount of timeneeded to bring the water to 2 ppm is highly dependent on the amount ofbather load in the water. A standard 24 hour dose or longer may beneeded to completely bring the water up. In one implementation of theAdd or BOOST command, the system switches from 2 amps to 4-4.5 amps torapidly generate chlorine. One run cycle every six hours may be used tomaintain uniform around the clock treatment.

In one embodiment, salt is measured each time the unit 11 generateschlorine as well as when requested by the user. The system measures thesalt level of the water by means of measuring the voltage and currentacross the cell 11. The voltage reading is then compared againstallowable limits. The salt concentration is normalized, and displayed onthe user interface. A voltage higher or current lower than specifiedreturns a low salt error and a voltage less or current higher thanspecified returns a high salt error.

If there is a low salt condition, an error may be sent to the spacontrols, triggering a “water care” icon to flash. The unit 11 may beallowed to continue to generate chlorine in this condition. The spacontrols or controller modulates available voltage or current to aregulated limit to automatically compensate for low salt or conductivitysituations. If there is a high salt condition, an error will be sent tothe spa controls, again triggering the water care icon to flash. In thiscase, the unit 11 will not generate chlorine until the salt level hasbeen corrected.

To prevent mineral scale on the electrodes 53, 55, 57, 59, polarityreversal may be used. The time period of the reversal is a function ofwater hardness and is preferably made adjustable to a user inputhardness reading. Rapid cycling of the electrodes will cause prematureelectrode failure. Therefore a dead band in the cycle may be implementedto allow the electrodes to discharge prior to the polarity reversal. Thedead band interval may be, for example, a minimum of 10-20 seconds.

At either initial start-up or at a maintenance event, the spa watershould be manually balanced. Once the spa water has been balanced itshould be super chlorinated (5 ppm). Super chlorination prepares thesystem for operation and immediate spa usage by cleaning the spa after aperiod of nonuse. After super chlorination, salt is added to the water.The spa control system may operate such that the water care icon isblinking to indicate that the salt level is low and/or the unit has notbeen initialized or programmed. Salt should be added slowly into thefilter compartment while all of the jets are operating. The jets shouldoperate an additional 10 minutes after the salt is fully added. Anexample of a target salt concentration is 1000 ppm. High demand userscan add up to 2000 ppm salt, which will lower the hours required togenerate chlorine and therefore lower the USE level. A salt levelreading is preferably taken every time the unit begins a generationcycle to ensure proper salt levels at start-up and during the timebetween water changes.

Typical operation of an illustrative system preferably requires a weeklychlorine and water quality check to ensure that the system is workingcorrectly. Although the user is not required to enter the chlorineconcentration, the value is needed to determine the use level. Over thecourse of the first month, the user may determine their Use Level bytaking a reading of the water before they enter the spa. If the chorinelevel is low, e.g., “1” or less, the user will want to increase the uselevel by one to increase the output. If the user finds that the chlorinelevel is 5 or higher, the user will want to drop the use level by oneand retest in a few days or a week. If the bather load is predictable,the use level may only need occasional adjustments.

If the bather load is sporadic, the user may want to perform a manualaddition. In such case, the user may enter the spa control menu andconfirm an addition (Add or Boost). The addition operation turns thesystem on immediately and operates the specified amount of timedetermined to elevate the chlorine level by 2 ppm (this depends onbather load and time and cannot be guaranteed). If the water is overlypolluted such that the actual bather load far exceeded the anticipatedbather load, a manual dichlor/MPS dose may be used and is compatiblewith the system.

Typically, the spa will require a monthly manual shock with MPS ordichlor to eliminate any accumulated waste. The oxidizer level should bebrought to and held at 5 ppm while all jets configurations and pumps areoperated for 30 minutes each. It is important to monitor pH at this timeas well to ensure that the water remains balanced.

Over time the water level in spa typically drops from evaporation orsplash out. When fresh water is added to the spa, it is important torebalance the water and monitor the salt concentration. The system mayemploy a conductivity sensor to determine the amount of salt in thewater and whether it is too high or too low. A water care icon may bearranged to blink to indicate that the salt is low and that more salt isneeded. Salt should be added in 0.25 lb (100 g) increments to ensurethat it is not over dosed.

While the apparatus and method have been described in terms of what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the disclosure is not limited to thedisclosed embodiments. It is intended to cover various modifications andsimilar arrangements included within the spirit and scope of theappended claims.

1. An apparatus comprising: a chlorine generating device comprising ahousing sized to fit within a central opening of a portable spa filter,and an electrode assembly positioned within the housing comprising aplurality of vertically disposed electrodes, the electrodes being spacedapart so as to define a water flow path between them; and an electricalcable extending out of said cylindrical housing and having a lengthselected to position said housing in said central opening and to extendto an interior surface of a portable spa.